It sounds like you have something that works for you, namely buying the seat that you want to fly in. It's hard to say how worth it status is for you as it differs for everyone based on differing travel patterns and things but things that people derive value from that come with status include:
1. Economy plus for free (potentially for companions as well)
2. Access to expanded saver award space (XN for economy, IN for business)
3. Free checked bags with an increased weight limit as well
4. Star alliance gold status
5. Pluspoints for upgrades
Many of these benefits are available through other channels as well, and if you're willing to buy up to J directly, then a lot of these will have a lot less value for you.